Performance of thin reinforced concrete slabs against low velocity repeated impact load

Abstract

The use of thin reinforced concrete slabs for buildings has more advantages than beam supported slabs, slabs with column capitals, and drop-down panels because of its easier construction and economic feasibility. However, it is susceptible to localized failure due to punching shear resulting in progressive collapse of the structure. Therefore, the attempt has been made to study the behaviour of thin reinforced concrete slabs 1200 × 1200 mm having thicknesses of 50 and 30 mm under repeated loading through the experiment and simulations. The mass of the impactor was 60 kg with 35 and 70° angular motion and the corresponding impact velocity were 2.62 and 4.97 m/s, respectively. Based on the member response under static conditions using analytical methods, the flexural failure was found to be more prominent and the ultimate flexural load for 50 mm thick slab was found to be 101.7% higher as compared to 30 mm thick slab. It was concluded that the resistance of the target was found to increase by 36% when the target thickness increased from 30 to 50 mm at 35° pendulum impact whereas the same was found to be 63% increment at 70° pendulum impact, during the first impact. Under repeated impacts, the impulse on both 30 and 50 mm thick slab was found to decrease gradually against 35° pendulum impact whereas the abrupt decrease in impulse was observed at 70° impact. The numerical analysis was performed using ABAQUS/EXPLICIT to predict the response of the slab under multi-impact loading. The numerical model was able to accurately predict the peak impact force on both 30- and 50-mm thick slab, up to the fourth impact.